Fixed issue that the declaration for vsg:createHeadLight() was not found

Fix geefr#51

Author: rhabacker

vsgvr/src/vsgvr/app/CompositionLayer.cpp

@@ -32,6 +32,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <vsg/app/View.h>
 #include <vsg/app/RenderGraph.h>
 #include <vsg/commands/PipelineBarrier.h>
+#include <vsg/nodes/Light.h>
 #include <vsg/ui/FrameStamp.h>
 #include <vsg/vk/SubmitCommands.h>